Miniature molded case circuit breakers, such as the miniature circuit breaker shown in U.S. Pat. No. 4,266,210, which is assigned to the same assignee as the present application, have a size limitation imposed upon them in order to fit the circuit breakers into panel boards of residential, office and light industrial applications. While the outer dimensions of a miniature circuit breaker are fixed, short circuit current magnitudes available from electrical utilities have increased, requiring the designers of miniature circuit breakers to seek new and improved operating and trip mechanisms which limit the energy let-through expressed by equation I.sup.2 t, where "I" is the current and "t" is the time from the onset of an overload to arc extinction. To limit energy let-through to an acceptable value, the circuit breaker must provide current limiting, which reduces the "I", and the time from the onset of an overload to arc extinction must be minimized. Thus, the circuit breaker must be extremely fast acting and capable of early contact separation upon the detection of an overload, and an arc voltage must be developed during contact opening which exceeds the driving voltage, to oppose the rise in short circuit current magnitude. In the limited volume available in the cavity of the molded casing, it is difficult to obtain a large contact opening distance, which thus limits the arc voltage obtainable, and it is difficult to obtain a substantial movement of the resulting arc, which is necessary to cool and quickly quench the arc without damage to the components of the circuit breaker. The limited volume available also results in a rapid increase in pressure inside the molded casing during arc interruption. While some pressure build up is beneficial in aiding arc interruption, the maximum pressure must be limited below the point which may damage the circuit breaker. Thus, it would be desirable, and it is an object of the invention, to (1) increase the contact separation distance, (2) increase arc movement, and (3) increase contact opening velocity, to provide a miniature circuit breaker having a significantly increased interruption rating. In addition, the operating mechanism of the circuit breaker must cause the actuating handle of the circuit breaker to remain in the "trip" position, once the movable contact arm crosses a toggle point.